Fluid-pressure tool



Nov'. 2 1926. 1,605,865 E; W. STEVENS FLUID PRESSURE TOOL Filed June 8.1923 2 Sheets-Sheet l f. .A l m ,Q `w\ om Nov. 2,1926. 6 K 1,605,865

E. W. STEVENS FLUID PRESSURE TOOL Filed June 8. 1923 2 Sheets-Sheet 2HTTORNEY Patented Nov. 2, 1926.

no sr r FTEN EDWARD W. STEVENS, 0F DETROEZI, MGHGAN, ASSGNOB TO CHCAGO'PNEUMATC TOOL COLTPANY, 01T* NEW YGRK, Y., A CRIPORATION 0F NEW JERSEY.

FLUID-raussunn Toon.

npplication filed .Tune 8, 1923.

rIhis invention relates to fluid pressure cperated tools having a pistonreciprocated by the operation of the piston, such as the valve andassociated parts which determine the cycle of operation of the tool andits eiiiciency and durability in service. Among the objects ot theinvention are to reduce wear ot1 parts, to promote smoothness andaccuracy of valve operation, to eliminate all tendency ot' the valve toflutter, and in general to improve the construction of previous devicesin the interest of more satisfactory servi-ce.

In order to facilitate the explanation of the novel features, theinvention is illus trated as embodied in a chipping hammner, but it isto be understood that the invention is not limited to the specifictorni, arrangement or operation of parts herein shown and described butis adapted to such other uses7 combinations and structural modiiicationsas tall within the scope oi' the appended claims.

In the drawings Figure 1 is a longitudinal sectional View through achipping hammer embodying the features of the invention substantiallyon` the line 1-1 ot Fig. 5 and showing the piston at the beginning ofits return stroke;

Figure 2 is a view similar to Fig. 1, but taken at a different angle asindicated by line 2-2 of Fig. 5, and showing the piston on its forward0r working stroke;

Figure 3 is a. 4fragmentary longitudinal sectional view substantially onthe line 3-3 of Fig. 5 showing the valve in elevation, the parts beingin the position shown in Fig. l;

Figure l is a transverse sectional view on the'line 1% of Fig. 1;

Figure 5 is a transverse sectional view on the line 5-5 of Fig. 1;

Figure 6 is a transverse sectional view on the line 6-6 of Fig. 1;

Figure 7 is a transverse sectional view on the line l7-7 ont Fig. 2; y

Figure 8 discloses in perspective the valve lid, the valve case and theadjacent end of the hammer cylinder in position to be assembled; and

Figure 9 is a transverse sectional view on the line 9-9 of Fig. 1.

The ham'mer as shown comprises a cyl- Serial No. 644,097.

inder A having alongitudinal bore for the piston B which reciprocatestherein. The 'forward end of the cylinder is partly closed by a bushingC in which is received the shank of a working tool D, the end ot whichis adapted to be struck by the reduced pro jecting head b of the piston.The rear end of cylinder A is closed by cap E which has screw threadedengagement therewith, the cap having attached thereto or integraltherewith the usual grasping handle E partly shown in Fig. 1. Clampedbetween the rear end of cylinder A and shoulder `e of the cap is thevalve housing comprising the valve case F and the valve lid G provi-dedwith various ports and passages controlled by a` sleeve valve H arrangedto reciprocate within the housing. The valve case and lid are lockedagainst movement relative to each other and to the cylinder by dowelpins j' on valve case F engaging suitable pin holes j" in the end of thecylinder and by other dowell pins f2 engaging cooperating pin holes invalvek lid G.

rihe hammer cylinder is provided with a plurality ot longitudinalpassages as indicated. The piston return passage 1() (Fig.

1) has a port 10 opening into the outer end of the piston chamber andcommunicates at its inner end with the longitudinal bore 11 in case Fwhich has a radial exhaust port v 11 and an angularly inclined inletport 112- of restricted size terminating adjacent lid G and registeringwith an opening g in the axially projecting annular flange got the lidwhich iits within the valve case F. The valve shift passage 12 (Fig. 1)has spaced ports 12 and 122 communicating with the piston chamberadjacent its center and outer end respectively and connects at its innerend withl a bore 13 in case F terminating adjacent the forward pressurearea 26 of valve H. The hammer cylinder has two eKhaust passages 14C(Fig. 2) having ports 14 opening into the piston chamber in the plane ofport 122 and communi eating with the angularly disposed bores 15 in thevalve case which lead directly to the exhaust chamber 16 whichcommunicates with the atmosphere through radial ports 16. Two live airpassages 17 (Fig. 8) in the hammer cylinder have diametrically opposedports 17 communicating with the piston chamber in the plane of port l2and at their inner end communicate with live air Ypassages 18 and 19 inthe valve case and are filled at all times with live motive fluid fromthe live air chamber e2 in the rear of cylinder cap E.

The valve H,- which controls the portsV and passages, has a forwardbearing sur.- face 20 cooperating with the forward bore 21 of case F, arearwardly disposed bearing surface 22 of greater longitudinaldimensions and slightly greater diameter cooperating with the bore 23 oflid G and an intermediate radially disposed projecting flange 2licooperating with the enlarged bore 25 of the case F and providingopposed pressure areas26 and 27 of substantially the same size. Therearward bearing surface 22 of the valve is provided with spaced shallowcircumferential grooves 2S, one of which is adjacent bearing surface 27and may serve to make the latter'slightly greater in area than surface26 if desired. Exhaust ports 15 connecting with passages 15 in the caseare controlled by surface 2() of the valve, restricted exhaust ports 30in the case (which communicate with the chamber in the rear of pressurearea 27 when the valve is inthe forward position shown in Fig. 2) byflange 24, and radial inlet ports 31 in lid H for supplying live motivefluid to the rear of the piston chamber by the rearward bearing surface'22 of the valve.

:To provide for access of motive fluid to i the rearwardlydisposedpressure area 27 ofthe valve without substantial sacrifice ofthe cooperating bearing surfaces ofthe valve and' valve housing, a novelconstruction is utilized, comprising one or more axially disposedrecesses or grooves in the bearing surfaces. l/Vhile these recesses orgrooves 82 may be cut in the valve housing, asV shown and by preferencefor reason of convenience and economy in manufacturing they are providedon the valve H in the bearing surface 22 intermediate annular grooves 28and are two in number (Fig. 7) at diametrically opposite points in orderto balance the thrust of the motive fluid on the valve and preventuneven wear. The motive fluid which thus reaches pressure area 27 ofrthe valve when in itsrearward position (Figjl) through grooves 32 isbled restricted'leak port 112 with the result that pressure is graduallybuilt up against area. 27. By a critical determination of the sizeof thegrooves 32 and port 112 sufiicient fluid is admitted to provide for thereturn stroke of the piston and for the built-up pressure to shift thevalve at the proper instant.

The cycle of operation of the hammer isv follows: lilith the parts inthe position shown in 1, the valve has just been moved to Iits rearwardposition through live air passing from the live air chamber e2 throughpassages 19, 18, 17, ports 17, around the reduced neck b2 of the piston,port 12, shift passage 12, port 13 to the pressure area 26, with theresult that the rear of the piston chamber is exhausting through theuncovered exhaust ports 15 in the valve case. Live air is being suppliedto pressure area 27 of the valve from chamber e? by ports 31, groove 31and the axial grooves 32 and is thence conducted through restricted port112, passage 11, return passage 10, port 10 to the front of the pistonto drive the latter rearwardly. The size of grooves relative to therestricted or bleed port 112 is such as to provide suiiicient built-uppressure against area 27 to cause shifting of the valve in a forwarddirection soon after the piston B reaches the broken line position ofFig. 1 uncovering exhaust port 1st wherebythe pressure behind area 26 ofthe valve is reduced` to the lower pressure obtaining at the front ofthe piston. The valve then shifts to the position shown in Fig. 2 intime to check the piston by the live motive fluid entering the pistonchamber through ports 31 before the piston can strike valve lid G, andat the same time the valve opens both return passage 10 and the chamberbehind pressureI area 27 to eX- haust through ports 30. Pressure of thelive motive fluid on the rear end face of the valve holds it in forwardposition untily the reduced neck b2 of the piston again enters the planeof'ports 12 andV 17. i

From the above it will be apparent that no area of the valve iscontinuously subjected tofluid pressure; that the shifting of the valveis leffected by alternately sub'- jecting opposed pressure areas thereofto live Vinotivefluid; that the valve is positively held in bothpositionsY without any tendency to flutter; that a portion of thepressure applied to one ofV said areas is utilized for the return strokeof the piston soy that this area issubjected to a built-up pressure;that by providing one or more axial grooves in the bearingsurface forthe valve'a greater bearing surface therefor is provided with consequentless wear;that this last named arrangement readily permits a criticaldetermination of the amount of pressure admitted to said area; that thelocation of live air portssuch as the grooves above mentioned atdiametrically opposite points balances the thrust upon the bodysubjected to the pressure with a consequent decrease in wear; and thatthe arrangement of bearing surfaces inthe valve case, lid and valvewhereby wear extends, to the inT ner edges of said surfaces in case andlid permits the easy insertion of oversizevalves when wear becomesappreciable.

1. In Va fluid pressure operated tool, in

lill

Ofi

combination, a cylinder having a piston chamber, a piston reciprooabletherein, a valve housing, admission and exhaust ports and passages insaid cylinder and housing, a sleeve valve for controlling said ports andpassages reciprocable in said housing and adapted to have said pistonpass therevvithin, a broad bearing surface on said valve adj acent apressure area thereof, said surface having an axial groove for admittingmotive fluid in restricted amount to said area in one position of saidvalve, and means uncontrolled by said piston for utilizing apredetermined portion of the motive fluid so adf mitted to drive saidpiston in one direction,

thus producing a building up of pressure against said area which becomeseffective at the proper' instant to shift the valve.

:2. In a fluid pressure operated tool, in combination, a cylinder havinga piston chamber, a piston reciprocable therein, a

valve housing, admission and exhaust ports and passages insaid cylinderand housing, an imperforate sleeve valve for controlling said ports andpassages reciprocable in said housing and adapted to have said pistonpass therewithin, a broad bearing surface on said valve adjacent apressure area thereof, said surface having diametrically opposite axialgrooves for admitting motive fluid in restricted amount to said area inone position of said valve, and means including a bleed portuncontrolled by said piston for conductingavvay a portion of the motivefluid so admitted to effect rearward movement of said piston, thusproducing a building up of pressure against said area Which becomeseffective at the proper instant to shift the valve.

Signed by Ine at Detroit Michigan this lst day of June 1923.

EDWARD W. STEVENS.

